Starting and operating circuits for fluorescent lamps



AMPS

Aug. 24, 1954 w, s. H. HAMILTON STARTING AND OPERATING CIRCUITS FOR FLUORESCENT L 5 Sheets-Sheet 1 Filed Jan. 15, 1952 INVENTOR: William 5-H.Hami1cun ATTORNEY.

Aug. 24, 1954 w. s. H. HAMILTON STARTING AND OPERATING CIRCUITS FOR FLUORESCENT LAMPS 5 Sheets-Sheet 2 Filed Jan. 15, 1952 i] a E in fies/lam) iallasflamp INVENTORZ William 5 H.Hami1tnn ATTORNEY 1954 w. s. H. HAMILTON 2,687,495

AMPS

5 Sheets-Sheet 3 STARTING AND OPERATING CIRCUITS FOR FLUORESCENT L Filed Jan. 15, 1952 INVENTOR H H amilcun William 5 ATTORNEY AMPS Aug. 24, 1954 w. s. H. HAMILTON STARTING AND OPERATING CIRCUITS FOR FLUORESCENT L 5 Sheets-Sheet 4 Filed Jan. 15, 1952 R m N w m William S.H-Hami1tnn,

ATTORNEY.

Aug. 24, 1954 w. s. H. HAMILTON STARTING AND OPERATING CIRCUITS FOR FLUORESCENT LAMPS 5 Sheets-Sheet 5 Filed Jan. 15, 1952 INVENTOR William 5.H-Hami1tun Patented Aug. 24, 1954 FLUORESCENT LAMPS STARTING AND OPERATING CIRCUITS FOR William S. H. Hamilton, Larchmont, N. Y. Application January 15, 1952, Serial No. 266,524

14 Claims.

This invention relates to starting and operating circuits for fluorescent lamps, and particularly to circuit arrangements for starting and operating a plurality of lamps (two or more) connected in series and designed to be operated from a line source of circuit supply, namely, lamps of various sizes designed to be operated on D. C. More particularly the invention relates to starting and operating circuit arrangements, for seriesconnected fluorescent lamps of the type requiring at least one filament to be heated to start them and which will start instantaneously or substantially so with proper heating of the filament and with application of line voltage alone, or for harder starting fluorescent lamps which require, according to ambient temperature conditions or lamp characteristics, that a surge impulse or inductive kick be given in order to start the lamps, or some of them, after they have been properly preheated. All lamps of a group of series-connected lamps of the first mentioned type will usually start simultaneously at moderate ambient temperatures when properly preheated, under line voltage alone, but some of the lamps of such a group may not start at low temperatures and require continued preheating beyond a normal period and an inductive kick to get them to start. The same difficulty may be encountered in restarting the lamps after the lamps have been operating for a long period and are very hot and the gas pressure therein is high enough to resist quick starting. Some of the lamps of a series of harder starting lamps, which always require an inductive kick to start them when normally preheated, will not start and below, but require further preheating and an inductive kick to start them even after one or more lamps of the series have already fired.

The present invention has for its object to overcome these objections and to provide circuit arrangements whereby lamps of the types described may be operated on line circuits of different kinds in such manner that all the lamps of a group or train may be started, either instantaneously or in a certain order, within a short period of time, and within cold or hot ambient temperature ranges. The invention further provides circuit arrangements allowing quick restarting of lamps after they have been turned off and it is desired to bodying the invention, for starting and operatat low temperatures, F.,

restart them, and provides special means to ensure the starting of lamps ing two or more lamps from different line sources of current supply,

Fig. 1 shows a circuit arrangement for starting and operating three fluorescent lamps in series from a D. 0. line;

Fig. 2 shows a circuit arrangement for start ing and operating four fluorescent lamps in series from a D. C. line;

Figs. 3, 4 and 5 show circuit arrangements for starting and operating two fluorescent lamps in series from a D. C. line, that shown in Fig. 5 having special provision for starting at cold temperatures; and

Figs. 6, '7, 8, 9 and 1 0 show circuit arrangements for respectively starting and operating four, five, six, eight and ten fluorescent lamps in series from a D. C. line, each of said circuits having special provision for starting at cold temperatures.

The various circuit arrangements shown for starting and operating instantaneous starting and harder starting lamps from different line sources of current and for starting and operating lamp groups at low temperatures when required may be divided into two groups, as follows:

Group 1.D. C. circuits, Figs. 1 to -5, inclusive, in which the line polarity is not reversed, but in which the line voltage is low enough (250 v. or less) to permit direct operation of the starter;

Group 2.D. C. circuits, Figs. 6 to 10, inclusive, in which the line polarity is not reversed, but in which the line voltage is too high to permit direct use of a starter and in which a, controlling relay is employed for coaction with and which is operated by the starter to effect starting of the lamps.

The circuits of Groups 1 and 2, Figs. 1 to 10, inclusive, are for lamps of the type which normally start substantially instantaneously but include a starter for operation in case the lamps do not start by the instant start method. In all circuits of these two groups only the negative filament of each lamp is preheated and the posi tive filament of each lamp may be open-circuited or short-circuited depending on the characteristics of the lamps used. All circuits of the two groups are each provided with a single starter having normally open contacts, and each circuit includes a primary preheating circuit closed by one or more relay switches and energized when the line circuit is first closed and the starter contacts are open, to preheat the lamps for a given time interval, and a secondary preheating circuit closed by the closing of the starter contacts at the end of such given time interval to continue the preheating of the lamps for a further period interval. Each circuit also contains a reactor and one or more relay coils controlling a relay switch or switches to break the primary heating circuit and cause the reactor to give an inductive kick when the starter contacts close, to fire a portion of the lamps and arranged to give a second inductive kick to fire the remaining unfired lamp or lamps when the starter contacts reopen. In all circuits the operating circuit for the lamps passes through all the lamps in series and the relay coils are in series therewith, so that when the lamps of a group are operating the relay coils will be energized to keep the relay switches and both preheating circuits open as long as the lamps are operating. In certain of the circuits provision is made for starting at cold temperatures by increasing the current fiow through the filaments of the lamps that have not fired during the time that the starter contacts are closed over what the current flow would be if this provision were not made. In most cases this also increases the current flow through the lamps that have fired, but, as the time that this increased current is applied is very short, it does no harm to the lamps.

In most of the circuits double-pole relays of suitable type are used, but their use is not obligatory, and the arrangement may be such that any number of relay contacts may be operated by the same relay coil provided the proper sequence is maintained.

With the foregoing understanding of the general construction and operation of the circuits. a detailed description of the construction and operation of each circuit will now be given.

Referring now more particularly to Fig. 1 of the drawings, l, 2 and 3 respectively designate fluorescent lamps of an instantaneously starting type, i. e., of a type which will generally start directly under applied line voltage when preheated for a short period of time, each lamp having a pair of spaced electrodes at and a, the negative electrode a being of filamentary type adapted to be heated and the positive electrode a being shown as open-circuited. Feed conductor leads b, b, b and a return conductor lead I) connect the electrodes in series with the line terminals T, T through the lamps when the lamps are operating and form an operating circuit common to the lamps. Conductor leads d, d, d are arranged to connect the filamentary electrodes 0, in series with each other and with the line terminals to provide a primary preheating circuit for simultaneously heating all the filamentary electrodes. The leads d, d, d contain the current limiting resistances x x 2: and have gaps normally closed by the relay switches or contacts R R C which thus normally connect the primary preheating circuit with the line. These switches are controlled by a relay coil RC arranged in the operating conductor section b so as to be energized when current fiows therethrough to cause the switches or contacts R R RP to open and break the primary preheating circuit. As shown, a reactor and a ballast lamp, so designated, are located in conductor b in such order between the line terminal T and electrode a of lamp I, between which reactor and ballast lamp, conductor 1) is connected to the input end of conductor d.

As stated, all the lamps 1-3 are of an instantaneously starting type, and generally such lamps when used singly and preheated to emission stage for a very short period of time, will start directly by the application of line voltage. When two or more such lamps are used in series, this is also usually true at the usual ambient temperatures, when first starting the lamps. However, the lamps do not always act in this manner and in order to insure their starting, I provide a starter whose contacts are normally open but which are arranged to close a predetermined time after the line circuit is closed, and in closing cause the firing of a portion of the lamps by breaking the inductive circuit thru the reactor, and also continue the preheating of the lamps that have not fired, until the starter contacts reopen, when another inductive kick. is given the lamps that have not fired, causing them to fire. The limiting resistances such as X X X in Fig. 1 are so proportioned as to insure the firing of certain lamps first, when they all fire simultaneously or substantially so and present the firing of the last lamp in the train first.

With the circuit arrangement shown in Fig. 1, if all the lamps do not fire simultaneously or substantially so, the starter contacts 3 close after a predetermined time to cause the primary preheating circuit to be broken, which fires lamps l and Z and establishes the secondary preheating circuit to continue the preheating of electrode a of lamp 3. The secondary preheating circuit in this circuit arrangement includes the conductors b, b, b b the operating lamps i and 2 and conductors e, e respectively connected with the conductor b and filament c of lamp 3 and with the contacts 5 of a normally open thermostatic switch S, said conductors forming a normally open circuit extending across the lamp 3 and adapted to be closed and opened. by the thermostatic switch. This switch is adapted to be heated to close its contacts by means of a heater 1-1 located in conductor 6, which heater is cut out of action when coil RC is energized to open the relay switches R R and R and break the primary preheating circuit. I'he thermostatic switch is or may be of a quick-snap type such as disclosed, for example, in my Patent No. 2,667,604 issued onv my prior application Ser. No. 48,564, filed August 24, 1948. Arc suppressing condensers c of suitable type are connected across the contacts of the relay switches and the contacts of the thermostatic switch.

In operation, when the line circuit is closed for a starting action preheating current flows through the negative filaments of all the lamps and through the heater H. The lamps being of an instantaneously starting type, all three lamps will normally fire simultaneously or substantially so under line voltage when their negative filaments are heated to emission state, with the result that coil RC will be energized and operate to cause relay contacts R R, E to open and break the primary preheating circuit and hold said circuit open as long as the lamps are operating. The breaking of the primary preheating circuit also cuts the heater H out of action to prevent the thermostatic switch contacts s from closing and allows the heater H to cool off. In the event, however, that all lamps do not fire simultaneously or nearly so, RC will not be energized and the primary preheating circuit will remain in action until the thermostatic switch contacts s close. The closing of these contacts s causes the relay coil to be energized and the relay to open contacts R R and RF.

5 Opening of contacts R and R causes an inductive kick to be given by the reactor which fires lamps I and 2. The closing of the starter contacts s also completes aforedescribed secondary preheating circuit. The completion of the secondary preheating circuit will cause the primary preheating circuit to be cut out of action and a fiow of preheating current to the negative filament a of lamp 3 will continue through the secondary preheating circuit until the thermostatic switch contacts s, being no longer heated by heater H, will cool off and open after another predetermined time interval and break the secondary preheating circuit. On the breaking of the secondary preheating circuit the sudden momentary arrest of current flow through the reactor will cause the reactor to give an inductive kick suificient to cause lamp 3 to fire. The firing of all three lamps within a short period of time will thus be ensured. Lamp N0. 3 cannot fire while the secondary preheating circuit is in action as it is short circuited by conductors e, e and the starter contacts 8. When all three lamps go into operation, as above do scribed, coil RC will be energized to hold open switches R R and R as long as the lamps. are operating.

The circuit arrangement shown in Fig. 2 designed for operating four lamps I, 2, 3, 4 in series is the same as that shown in Fig. 1 with the exception of the arrangement of the starter between lamps 3 and A, with the addition of the conducting connection d leading from conductor 19 to filament a of lamp t and containing relay contacts R and resistance at, and the use of two relay coils RC EC in. conductor b coil RC operating to control the switches R R and coil RC operating to control the switches R R The operation of this circuit arrangement is the same as that previously described with reference to Fig. 1,

with the exception that if all four lamps do not start simultaneously or substantially s0, lamps I, 2 and 3 are fired by the closing of the starter contacts s, which energizes relay coils RC RC opening contacts R R R and R and also continues the preheating of filament a of lamp 4- until the starter contacts s reopen, breaking the inductive circuit thru the reactor, ballast lamp and lamps I, 2 and 3, causing lamp l to fire. Lamp l cannot fire while the starter contacts s are closed as it is shortcircuited by them and conductors e and c This circuit arrangement is advantageous for operating four T-12 or four 12" T-8 lamps across a 230-240 volt source of C. current supply.

Fig. 3 shows a circuit arrangement for operating two series connected lamps I and 2 from a D. C. line circuit, the operating and preheating circuit elements of which will be readily understood from the description applying to the circuit organization shown in Fig. 1. If both lamps in the circuit organization shown in Fig. 3 do not fire simultaneously or substantially so, when the filamentary electrodes of both lamps are preheated, and line voltage applied, then the secondary preheating circuit containing conductors e, e, d, b will be thrown into action to fire lamp 2 and to continue the preheating of the filamentary electrode of lamp I until the secondary preheating circuit is broken and the reactor operates to give an inductive kick to. start lamp I.

Fig. 4 shows a circuit arrangement for use in connection with a D. C. source of current supply for operating two fluorescent lamps in series, and starting them automatically by means 6. of one thermostatic switch and a relay. This circuit is desirable for use when -120 volts D. C. is available, and special arrangements of lamps are required, as in connection with mirrors, where the lamps may be mounted alongside of or above and below a mirror. In this circuit arrangement the conductor 1) is normally connected to a preheating conductor section b containing a current limiting resistance .12 by an upper normally closed self-closing switch member or set of contacts R, of a double pole relay which also includes a lower normally closed self-closing switch member or set of contacts R and an actuating coil RC controlling the action of both switch members or sets of contacts. Conductor section b leads to one end of the negative filament a of the fluorescent lamp I, the terminals of whose positive elec trode a are short-circuited and connected to the operating conductor section b leading from the last lamp. The other end of the filament a of lamp No. I is connected by conductor 1) to preheating and operating conductor sections 03 and b", respectively, in which are respectively arranged the heating element H of the normally open thermostatic switch S and the relay 001 RC. The preheating conductor section 03 extends to and is normally connected with and adapted to be disconnected from the preheating conductor d by the relay switch R Conductor 12" contains the current limiting resistances r and x and leads to one end of the negative filament a of the lamp No. 2, the opposite end of which filament is connected with the conductor b leading to the negative line terminal T. Conductor b is connected through coil RC with the positive filament a of lamp No. l, which is short-circuited. The conductors e, e of the normally open thermostatic switch circuit are connected to the contacts s of the thermostatic switch S and to the conductors b and d' and hence across the filaments of lamp No. 2 which is connected by conductors b, b" in series with lamp No. I.

In operation of this lamp circuit, current in starting flows from the positive side of the line through the reactor, conductor b the upper contacts R of the relay, resistance the negative filament a of lamp No. I, the heater ele ment H of the thermostatic switch, the lower contacts R of the relay, resistances x the negative filament a of lamp N0. 2, and thence through conductor b to the negative side of the line. A circuit is also established from the reactor through the ballast lamp to the positive filament a of lamp No. I, and from the negative filament a of lamp No. I to the positive filament a of lamp No. 2 through the coil RC of the relay. Ordinarily both lamps will fire within a second or two after both negative filaments have been heated. When this occurs, current passes through the gas of lamp No. l thru the relay coil RC, to the positive filament of lamp No. 2 and through the gas of lamp No. 2 to the negative side of the line. When the coil of the relay is energized, it opens both sets of relay contacts, cutting the current off from the resistances 1: :2 41: and heater element H.

In case the lamps do not fire on the application of line voltage alone, current will contiue to flow through the heater element H until the thermostatic switch is sufiiciently heated to close its normally open contacts 8. Closing of these contacts causes the relay to pick up and break its upper set of contacts R whereupon the reactor gives an inductive kick which causes lamp No. i to fire. A circuit is then established from the ballast lamp through lamp No. l, the relay coil RC, the contacts of the thermostatic switch, resistance :r and negative filament of lamp No. 2 back to the negative side of the line. The current to the heater element H is cut off by the opening of the lower set of contacts R of the relay at the same time. When the heater element H has cooled down sufiiciently, contacts 5 reopen, giving an inductive kick to lamp No. 2 which is suificient to fire it also. Both lamps then continue to burn, with the relay energized and current on" of the resistances and the heater element 1-1. If the line circuit is broken the relay drops out immediately and the circuit is ready to restart again upon the reclosing of the line circuit.

Fig. 5 shows a circuit arrangement similar to that of 3 for operating two series connected lamps from a D. C. line circuit, but which includes special means for starting the lamps at cold ambient temperatures. The special means provided in this circuit for such purpose consists in the addition of the resistance X connected in conductor 6 and between the relay coil RC and the thermostatic switch contacts. The starter contacts when closed to establish the secondary preheating circuit will thus connect resistor K to the low side of the relay coil RC, ahead of the ballast lamp. This picks up the relay opening contacts R R and fires lamp No. 2. By properly proportioning the resistance X a larger current is fed into the filament a of lamp No. i and through. lamp No. 2 to the filament a of the latter while the starter contacts are closed than is possible with the circuit organization shown in Fig. 3 where the current is limited by the ballast lamp, since a ballast lamp selected for proper current supply during normal operation will usually not pass sufiicient current to ensure starting of the second lamp at cold temperatures such as F., and below. The starting of lamp No. 2 can be ensured at such low temperatures by selecting resistors X and X of a value to give sufficient preheat but with lamp No. 2 operating and the starter contacts closed the current would be too low to properly preheat the filament of lamp No. i without the use of resistor X which allows an amplified current to be supplied to start lamp No. into operation.

In 6 to 10 showing circuit arrangements for operating lamps from D. C. current sources in which the line polarity is not reversed, and in which the line voltage is too high to permit direct starting of the lamps, special means are provided including resistances selected and arranged to give the best results for substantially instant starting. These circuit arrangements also include special means for starting the lamps at cold temperatures.

Fig. 6 shows a circuit arrangement for four lamps which is generally similar to that shown in Fig. 2, but which includes an added relay coil RC and resistor arranged in conductor e of the secondary preheating circuit, a normally open shunt circuit e arranged in conductor d about the switch PP, normally open switches R and. R arranged in conductor b and circuit 6' and controlled by the coil RC and a resistor m in the circuit 6'. Resistor m and contacts R. above described provide booster means for increasing the amount of preheating current which may be supplied under cold Weather or other adverse conditions to cause those lamps to fire which do not fire when the starter contacts close. In starting, current flows from the positive side of the line through the reactor, resistor m contacts R, negative filament of lamp No. I, contacts R resistor m negative filament of lamp No. 2, resister :2 contacts Pt", negat e fi t f p No. 8, contacts R resistor heater H, resistor 0: negative filament of lamp No. 4, and thence to the negative side of the line. This preheats the negative filament of each lamp. In addition, connections are made to the positive filament of each lamp. Resistors :c 32 and the sum of resistors :c and (r are selected to give the best results for instant starting, and to prevent lamp 4 firing before lamps l, .2 and 3. Usually under favorable ambient conditions all four lamps will fire instantaneously or substantially so, and when they do coils RC and RC are energized by current flowing through the lamps, and they in turn open contacts R F", R and R thus breaking the primary preheating circuit and the circuit through heater H. The lamps will then continue to operate with current fiOWil'lg from the positive side of the line through the reactor and ballast lamp to the positive filament of lamp No. I and through lamps i, 2 and 3 in turn and through coils RC and RC and lamp No. 4. to the negative side of the line. In this starting action the starter performs no function. Should, however, the lamps fail to start under this condition, the preheating action through the primary preheating circuit continues until heater H causes the starter contacts 3 to close. When they do they connect relay coil RC across resistor :2 applying sufiioient voltage to it to cause it to pick up and close the contacts R and R Contacts R when closed energize coils RC and RC and these relays open contacts R R R R breakingthe primary preheating circuit through resistors x :0 and and heater H, causing lamps 2 and 3 to fire. Lamps No. i and No. l do not fire at this time, because lamp No. 4 is substantially short circuited by contacts R and resistor r and lamp No. i is substantially short circuited by contacts R and resistors 31 and 0: The secondary preheatin circuit is thus established causing through the closing of the relay contacts R extra current to be supplied to the negative filaments of lamps Nos. i and i and through lamps Nos. 2 and 3 over what the ballast lamp alone would supply, so that when the contacts 5 of the starter S reopen, due to heater H cooling oii, they open the circuit of coil RC causing the inductive circuit through the reactor to be broken and enough kick given to fire lamps Nos. i and '1 even at temperatures of 0 and below. The circuit through lamps Nos. 2 3 is at this time broken momentarily, but they refire immediately. After the lamps have fired, current from the positive side of the line flows through the reactor and ballast lamp to the positive filament of lamp No. I, through each of the lamps Nos. i, 2 and 3 in turn. through coils RC and EC to the positive filament of lamp No. d and through the gas in the lamp to the negative filament and thence to the negative side of the line. Thereafter, so long as the lamps continue to operate coils RC and RC will hold both the primary preheating circuit and. the secondary preheating circuit open. Coil RC will not then be energized because heater H is cut out of action and the contacts 3 of the starter are normally open. Should the line circuit be opened. contacts R R R and R will immediately return to their starting position, ready to initiate another starting action when the line circuit is reclosed. Should provision for cold starting not be required, contacts Pu and resistor 50 may be omitted and the circuit will function properly at normal temperatures.

Fig. 7 shows a D. C. circuit arrangement for five lamps which is similar to Fig. 6 except as to the addition of lamp N o. 5 and preheating circuit conductor section d containing relay switch R and resistor x addition of relay coil RC and arrangement of coil RC in conductor b Coil RC here controls contacts R and R coil RC controls contacts RP and R and coil RC controls contacts E The operation of this circuit arrangement is substantially the same as that of Fig. 6 except that when the starter contacts close they cause the firing of lamps Nos. 2, 3 and 4, and when they reopen. they cause the firing of lamps Nos. i and 5. The provision for cold starting is in contacts R and resistors 22 and which enable additional current to be passed through the negative filaments of lamps Nos. l and and through lamps 2, S and t while the starter contacts are closed. thus ensuring adequate inductive kick being obtained when the starter contacts reopen to fire lamps Nos. I and 5 at cold temperatures (0 F. or below).

Should provision for cold starting not be required contacts R and resistor :0 may be omitted.

Fig. 8 shows a D. C. circuit arrangement for six lamps in series with provision for cold starting. This circuit is substantially the same as that shown in Fig. '7, with the addition of conductor b relay contacts R and resistor :8 and rearrangement of the parts for a change in firing of the lamps. Coil RC here controls the contacts R and R coil RC controls the contacts R and R coil RC controls the contacts R and R and coil RC controls the contacts R and R The arrangement is such that when the starter contacts close, coils RC and RC only are energized to open their contacts to fire lamps 3, a and 5. Coil RC is not energized under this condition so that the supplementary current for starting at cold temperature is supplied through contacts R R R and resistors :c :11 and x When the starter contacts reopen, however, they cause the energization of all the coils and the firing of lamps I, 2 and 6.

Fig. 9 shows a circuit arrangement for operat-- ing eight fluorescent lamps in series from a D. C. line. This circuit arrangement is generally the same as that shown in Fig. 8 with the addition of lamps Nos. 1 and 8 and the noted conductor sections and relays. Here coil RC controls contacts R and R coil RC controls contacts R and R coil RC controls contacts R and H coil RC controls contacts R and R and coil RC controls contacts R R and R. This circuit also operates substantially in the same manner as Fig. 8. If the lamps do not start instantaneously or nearly so, the starter contacts in closing cause relay coils RC RC and RC to be energized, firing lamps 3, l, 5 and 6. Lamp No. l is prevented at this time from firing by contacts R, and lamp No. 8 by contacts R and resistor m lamps Nos. l and 2 by contacts R R R and resistors x :0 and r Contacts R and resistor :0 provide the extra current to ensure the firing of lamps Nos. I, 2, 1 and 8 when the starter contacts reopen. When operating, relay coils RC RC RC and RC are all energized and hold the primary and secondary preheating circuits open by holding contacts R to R inclusive, open,

10 which in turn prevent the starter from closing its contacts s and energizing coil RC which controls contacts R R and R.

Should provision for cold starting not be required contacts R, R, and resistor 3: may be omitted.

Fig. 10 shows a circuit arrangement for operating 10 15" T-l2 lamps in series on 500-650 volts D. C. or 10 24 T-12 lamps in series on some higher special D. C. voltage. This circuit arrangement is substantially the same as that shown in Fig. 9 with the addition of lamps 9 and i8, relay coil RC relay contacts R and R resistors x and x and arrangement of the interconnections. This circuit also operates in the RC and RC are not energized, and lamp No. I0 is prevented from firing because it is essentially short circuited by contacts R and resistor Contacts B and resistor ac provide the extra current to ensure the firing of lamps Nos. l, 2, 3, 4 and 10 when the starter contacts reopen.

Should provision for cold starting not be required contacts R and resistor w may be omitted. Circuit arrangement operating on the principle of Figs. 7 to 10, inclusive, may be used for operating any odd number of lamps or more than be necessary.

While the circuit arrangements for starting and operating circuits embodying two or more lamps as herein disclosed are preferred, it is to be understood that variations falling Within the circuit at a predetermined time interval after the closing of the line circuit and then opening the secondary preheating circuit at a predetermined later time interval and operating on each of such opening and closing action to cause the reactor to give an inductive kick to fire the unstarted lamp or lamps.

2. In a starting and operating circuit for a train of gaseous discharge lamps embodying two or more lamps connected in series, each lamp having spaced electrodes, at least one of which is a filamentary electrode adapted to be heated, an operating circuit for connecting the lamp electrodes in series for operation froma line source of current, a primary preheating circuit including the filamentary electrodes and a reactor, electromagnetic switching means for normally closing said primary preheating circuit and connecting it with the line for preheating the filamentary electrode of each lamp when the line circuit is closed for a lamp starting operation, electromagnetic control means arranged in series in the operating circuit for operating and causing said switching means to break the primary preheating circuit when one or more lamps in the train fire, a normally open secondary preheating circuit including the reactor and connected with the filamentary electrode of the last lamp of the train and arranged to be closed to continue the preheating of the filamentary electrode of any lamp or lamps not fired during a predetermined time interval of operation of the primary preheating circuit, and a normally open thermostatic switch energized for successive closing and opening actions when the line circuit is closed for first closing the secondary preheating circuit at a predetermined time interval after the closing of the line circuit and then opening the secondary preheating circuit at a predetermined later time interval, said switch operating on each of such opening and closing actions to cause the reactor to give an inductive kick to fire the unstarted lamp or lamps.

3. In a starting and operating circuit for a train of gaseous discharge lamps embodying at least two lamps connected in series, each lamp having a pair of spaced electrodes, at least one of which is of filamentary type adapted to be heated, an operating circuit for connecting the lamp electrodes in series for operation from a line source of current, a primary preheating circuit including a reactor and series connections between the filamentary electrodes of the lamps and a line terminal, a switch in each connection normally closing said primary preheating circuit and connecting it with the line for preheating the filamentary electrode of each lamp when the line circuit is closed for a lamp starting operation, controlling means arranged in series in the operating circuit for opening said switches to break the primary preheating circuit on the firing of one or more lamps in the train, a normally open secondary preheating circuit including the reactor and connected with the filamentary electrode of the last lamp of the train and the preceding lamp and arranged to be closed to continue the preheating of the filamentary electrode of any lamp or lamps not fired during a predetermined time interval of operation of the primary preheating circuit, and a normally open thermostatic switch energized for successive actions when the line circuit is closed for first closing the secondary preheating circuit at a predetermined time interval after the closing oi the line circuit and then opening the secondary preheating circuit at a predetermined later time interval and operating on each of such opening and closing actions to cause "he reactor to give an inductive kick to fire the unstarted lamp or lamps, said secondary preheating circuit including means for increasing the value of the current passing through said filamentary electrodes of the unfired lamps of the train when the thermostatic switch is closed to ensure firing of said unfired lamps at cold temperatures, 0 F., or below, when said switch opens.

4. In a starting and operating circuit for a plurality of gaseous discharge lamps embodying two or more lamps connected in series, each lamp having spaced electrodes, at least one of which is a filamentary electrode adapted to be heated, an operating circuit for connecting the lamp electrodes in series for operation from a line source of current, a primary preheating circuit including a reactor and connections between the filamentary electrodes, switching means in said connection for normally closing said primary preheating circuit and connecting it with the line for preheating the filamentary electrode of each lamp when the line circuit is closed for a lamp starting operation, controlling means arranged in series in the operating circuit for opening said switching means to break the primary preheating circuit on the firing of one or more lamps in the train, a normally open secondary preheating circuit including the reactor and connected between the filamentary electrode of the last lamp and preceding lamps of the train and arranged to be closed to continue the preheating of the filamentary electrode of any lamp or lamps not fired during a predetermined time interval of operation of the primary preheating circuit, a thermostatic switch energized for successive actions when the line circuit is closed for first closing the secondary preheating circuit at a predetermined time interval after the closing of the line circuit and then opening the secondary preheating circuit at a predetermined later time interval and operating on each of such opening and closing actions to cause the reactor to give an inductive kick to fire the unstarted lamp or lamps, normally open booster circuits for supplying preheating current of increased value to the secondary preheating circuit when the thermostatic switch is closed, and switches controlled by said controlling means to close the booster circuits.

5. In a starting and operating circuit for a train of gaseous discharge lamps embodying two or more lamps connected in series, each lamp having spaced electrodes, at least one of which is a filamentary electrode adapted to be heated. an operating circuit for connecting the lamp electrodes in series for operation from a line source of current, a primary preheating circuit including the filamentary electrodes and containing a reactor, controlling means including a control switch for normally closing the primary preheating circuit of each lamp and connecting it with the line for preheating the filamentary electrode of each lamp when the line circuit is closed for a lamp starting operation, a relay coil or coils arranged in series in the operating circuit for opening said switches to break the primary preheating circuit when one or more lamps in the train fire, a normally open secondary preheating circuit including the reactor and connected with the filamentary electrode of the last lamp of the train and arranged to be closed to continue the preheating of the filamentary electrode of any lamp or lamps not fired during a predetermined time interval of operation of the primary preheating circuit, a thermostatic switch energized for successive actions when the line circuit is closed for first closing the secondary preheating circuit at a predetermined time interval after the closing of the line circuit and then opening the secondary preheating circuit at a predetermined later' time interval and operating on each of such opening and closing actions to cause the reactor to give an inductive kick to fire the unstarted lamp or lamps, normally closed booster circuits for supplying preheating current of increased value to the secondary preheating circuit when the thermostatic switch is closed, and switches controlled by said controlling means to open the booster circuits.

6. In a starting and operating circuit for a plurality of gaseous discharge lamps connected in series, each lamp having spaced electrodes at least one of which is a filamentary electrode adapted to be heated, an operating circuit for connecting the lamp electrodes in series for operation from a line source of current, a primary preheating circuit containing a reactor and including the filamentary electrodes and connections therebetween, a switch in each of said connections for normally closing said circuit and connecting it with the line for preheating the filamentary electrode of each lamp when the line circuit is closed for a lamp starting operation, coils arranged in series in the operating circuit, each coil being operative for opening a group of switches to break the primary preheating circuit when a certain number of lamps fire, a normally open secondary preheating circuit including the reactor and connected with the filamentary electrode of the last lamp of the series for breaking the primary preheating circuit if not previously broken by a lamp firing action and continuing the preheating of the filamentary electrodes of any lamps not fired during the time interval of operation of the primary preheating circuit, and a thermostatic switch energized for action when the line circuit is closed for first closing and then opening the secondary preheating circuit at predetermined time intervals following the closing of the line circuit and operating on each of such actions to cause the reactor to give an inductive kick to fire the unstarted lamp or lamps.

7. A starting and operating circuit for a plurality of gaseous discharge lamps connected in series, each lamp having at least one filamentary electrode adapted to be heated to start the lamp, arranged for operation from a D. C. line of fixed polarity, a primary preheating circuit containing a reactor for preheating the negative filament of each lamp, a thermostatically operated starter having normally open contacts adapted to close a predetermined time after the closing of the line circuit in case the lamps have not fired due to the application of primary preheating current and line voltage alone, said starter contacts when closing to cause one or more relays to break the primary preheating circuit through the reactor causing an inductive kick sufiicient to fire a portion of the lamps, said starter contacts when closed to cause a secondary preheating circuit also containing aforesaid reactor to be established for continuing the preheating of the negative filaments of the lamps that have not fired until said starter contacts reopen at a predetermined time after the opening of the primary preheating circuit, said starter contacts in reopening to cause the secondary preheating circuit through the aforesaid reactor to be broken causing sufiicient inductive kick to be generated to fire the remainder of the lamps, and an operating circuit connecting all the lamps in series and in series with one or more relay coils, the contacts associated therewith being arranged to keep open both the primary and the secondary preheating circuits while the lamps are operating.

8. A starting and operating circuit for a plurality of gaseous discharge lamps connected in series, each lamp having at least one filamentary electrode adapted to be heated to start the lamp, arranged for operation from a D. C. line of fixed polarity, a primary preheating circuit containing a reactor for preheating the negative filament of each lamp, a thermostatically operated starter having normally open contacts adapted to close a predetermined time after the closing of the line circuit in case the lamps have not fired due to the application of primary preheating current and line voltage alone, said starter contacts when closing to cause one or more relays to break the primary preheating circuit through the reactor causing an inductive kick sufficient to fire a portion of the lamps, said starter contacts when closed to cause a secondary preheating circuit also containing aforesaid reactor to be established for continuing the preheating of the negative filaments of the lamps that have not fired until said starter contacts reopen at a predetermined time after the opening of the primary preheating circuit, said starter contacts in reopening to cause the secondary preheating circuit through the aforesaid reactor to be broken causing sufiicient inductive kick to be generated to fire the remainder of the lamps, said secondary preheating circuit also including a portion of said primary preheating circuit, and an operating circuit connecting all the lamps in series and in series with one or more relay coils, the contacts associated therewith being arranged to keep open both the primary and the secondary preheating circuits While the lamps are operating.

9. A starting and operating circuit for a plurality of gaseous discharge lamps connected. in series, each lamp having at least one filamentary electrode adapted to be heated to start the lamp, arranged for operation from a D. C. line of fixed polarity, a primary preheating circuit containing a reactor for preheating the negative filament of each lamp, a thermostatically operated starter having normally open contacts adapted to close a predetermined time after the closing of the line circuit in case the lamps have not fired due to the application of primary preheating current and line voltage alone, said starter contacts when closing to cause one or more relays to break the primary preheating circuit through the reactor causing an inductive kick sufiicient to fire a portion of the lamps, said starter contacts when closed to cause a secondary preheating circuit also containing aforesaid reactor to be established for continuing the preheating of the negative filaments of the lamps that have not fired until said starter contacts reopen at a predetermined time after the opening of the primary preheating circuit, said secondary circuit including a portion of the primary preheating circuit and including means for increasing the secondary preheating current to a value sufiicient to ensure the firing of the remainder of the lamps at cold temperatures such as 0 F. and below when said secondary preheating circuit is broken, said starter contacts when reopening causing the secondary preheat ing circuit through the aforesaid reactor to be broken and an inductive kick to be given thereby to fire the remainder of the lamps, and an operating circuit connecting all the lamps in series and in series with one or more relay coils, the contacts associated therewith being arranged to keep open both the primary and the secondary preheating circuits while the lamps are operating.

10. A starting and operating circu't for a plurality of gaseous discharge lamps connected in series, each lamp having at least one filamentary electrode adapted to be heated to start the lamp, arranged for operation from a D. C. line of fixed polarity, a primary preheating circuit containing a reactor for preheating the negative filament of each lamp, a thermostatically operated starter having normally open contacts adapted to close a predetermined time after the closing of the line circuit in case the lamps have not fired due to the application of primary preheating current and line voltage alone, said starter contacts when closing to cause one or more relays to break the primary preheating circuit through the reactor causing an inductive kick sufficient to fire a portion of the lamps, said starter contacts when closed to cause a secondary preheating circuit also containing aforesaid reactor to be established for continuing the preheating of the negative filaments of the lamps that have not fired until said starter contacts reopen at a predetermined time after the opening of the primary preheating circuit, said starter contacts in reopening to cause the secondary preheating circuit through the aforesaid reactor to be broken causing sufficient inductive kick to be generated to fire the remaindeer or the lamps, said secondary preheating circuit also being so arranged as to increase the preheating current to a value sufficient to ensure the firing of the remainder of the lamps at cold temperatures such as F. and below, when said secondary preheating circuit is broken, and an operating circuit connecting all the lamps in series and in series with one or more relay coils, the contacts associated therewith being arranged to keep open both the primary and the secondary preheating circuits while the lamps are operatmg.

11. A starting and operating circuit for a plurality of gaseous discharge lamps connected in series, each lamp having at least one filamentary electrode adapted to be heated to start the lamp, arranged for operation from a D. C. line of fixed polarity, a primary preheating circuit containing a reactor for preheating the negative filament of each lamp, a time delay device having normally open contacts adapted to close a predetermined time after the closing of the line circuit in case the lamps have not fired due to the application of primary preheating current and line voltage alone, said time delay device contacts when closing to cause one or more relays to break the primary preheating circuit through the reactor causing an inductive kick sufficient to fire a portion of the lamps, said time delay device contacts when closed to cause a secondary preheating circuit also containing aforesaid reactor to be established for continuing the preheating of the negative filaments of the lamps that have not fired until said time delay device contacts reopen at a predetermined time after the opening oi the primary preheating circuit, said time delay device contacts in reopening to cause the secondary preheating circuit through the aforesaid reactor to be broken causing sufficient inductive kick to be generated to fire the remainder of the lamps, and an operating circuit connecting all the lamps in series and in series with one or more relay coils, the contacts associated therewith being arranged to keep open both the primary and the secondary preheating circuits while the lamps are operating.

12. In a, starting and operating circuit for a fluorescent lamp system comprising a pair of fluorescent lamps arranged to be operated in series from a line source of current supply, each lamp having spaced negative and positive electrodes, a preheating connection between the negative electrode of one of the lamps and positive side of the line, a relay switch for interrupting said connection, an operating connection between the positive electrode of said lamp and the positive side of the line, said connection containing a reactor, a second preheating connection leading to the negative electrode of the other lamp, said electrode having a connection with the negative side of the line, a relay switch for interrupting the second preheating connection, said preheating connection including a heater, operating connections including a relay coil between the negative electrode of the first named lamp and positive electrode of the second named lamp and a normally open connection between the negative electrode of the first named lamp and the preheating connection leading to the negative electrode of the second named lamp, said normally open connection including the relay coil, and a normally open thermostatic switch arranged to be heated by the heater to close said normally open connection.

13. A starting and operating circuit for a pair of fluorescent lamps connected in series to a D. C. line or" fixed polarity, each lamp having at least one filamentary electrode adapted to be heated to start the lamp, a primary preheating circuit containing a reactor for preheating the negative filament of each lamp, a secondary preheating circuit including a thermostatically operated starter having normally open contacts arranged to close a predetermined time after the closing of the line circuit in case the lamps have not fired due to the application of primary preheating current and line voltage alone, the contacts of said starter when closing to cause relay contacts to break the primary preheating circuit through the reactor causing an inductive kick to start the lamp, said starter contacts when closed to establish the secondary preheating circuit, also containing the aforesaid reactor to continue the preheating of the negative filament of the second lamp until said starter contacts reopen at a predetermined time after the opening of the primary preheating circuit, said starter contacts in reopening to break the secondary preheating circuit through the aforesaid reactor to cause an inductive kick to fire the second lamp, and an operating circuit connected in series with both lamps including a relay coil, the contacts associated therewith being arranged to keep open both the primary and secondary preheating circuits while the lamp is operating.

14. A starting and operating circuit for a pair of fluorescent lamps connected in series to a D. C. line of fixed polarity, each lamp having at least one filamentary electrode adapted to be heated to start the lamp, a primary preheating circuit containing a reactor for preheating the negative filament of each lamp, a secondary preheating circuit including a thermostatically operated starter having normally open contacts arranged to close a predetermined time after the closing of the line circuit in case the lamps have not fired due to the application of primary preheating current and line voltage alone, the contacts of said starter when closing to cause relay contacts to break the primary preheating circuit through the reactor causing an inductive kick to start the lamp, said starter contacts when closed to establish the secondary preheating circuit, also containing the aforesaid reactor to continue the preheating of the negative filament of the second lamp until said starter contacts reopen at a predetermined time after the opening of the primary preheating circuit, said starter contacts inreopening to break the secondary preheating circuit through the aforesaid reactor to cause an inductive kick to fire the second lamp, and an operating circuit connected in series with both lamps including a relay coil, the contacts associated therewith being arranged to keep open both the primary and secondary preheating circuits while the lamp is operating, said secondary preheating circuit also having means to increase the preheating current to a value sufficient to cause the firing of the second lamp at cold temperatures such as 0 F., and below, when said secondary preheating circuit is broken.

References Cited in the file of this patent UNITED STATES PATENTS 

